CONTENTS

 1     Introduction
 2     Scope
        2.1     General
        2.2     Applicability
 3     Possible benefits of the PCIs
        3.1     For implementors
        3.2     For users
        3.3     For carriers
 4     PCIs requirements
        4.1     Independence
        4.2     Dependency
        4.3     Flexibility
        4.4     Extensibility
        4.5     Multiple applications
        4.6     Easy implementation and testing
 5     General guidelines for defining PCIs
        5.1     Location of the interface
        5.2     Functional description
        5.3     Formal description
        5.4     Presentation of the information
 6     General functional model
 7     Application related interfaces
        7.1     Definitions
        7.2     General features
 8     Network/Protocol related interfaces
        8.1     Definition
        8.2     General features
Annex A – Definitions
Appendix I – Examples
        I.1     Telefax 3 on PSTN
        I.2     ISDN Lower Layer Module